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Digital Conversions

When an analog audio signal arrives at the inputs of your audio interface, it must be converted into digital information before the computer can deal with it. This process is called analog to digital conversion—handled by the Analog to Digital Converter (ADC) of your audio interface.

At the other end of the signal path, the digital signal needs to be reconverted into an analog signal, so that it can be heard through analog audio playback systems—an amplifier and speakers. This process is called digital to analog conversion, which is performed by the Digital to Analog Converter (DAC) of your audio interface.

About Bits and Sampling Rates

When recording a sound into your computer, the ADC of your audio interface takes a sample of the sound source, a specific number of times per second. This is known as the sample rate, which is measured in kHz (kilohertz—kilo means thousand) or “x” thousand samples per second. The higher the rate, the more samples the AD converter takes, and the more accurate the digital representation of the sound will be.

Put another way, imagine each sample to be a photograph of a concert that you are trying to describe to a friend. If you had taken one photo every 10 minutes, you’d find it hard to describe the great light show. If you took a thousand photos during that 10 minutes, your friend could easily see what happened. This increased “rate,” or number of photos (samples), delivers a far more accurate overall picture of what happened. This is how sampling works. The more “sonic photos” taken, the more accurately the sound is represented over time. A videotape recording of the concert—running at 25 frames (samples) a second, would give an even more accurate idea of the light show.

Common sample rates used in audio production include: 44.1 kHz or 48 kHz, and high- end systems may use rates from 96 kHz up to 192 kHz.

The sampling resolution—expressed as bit values—determines the precision of the measuring scale used to store (the numbers of) each sample. Remember that computers store audio files as digital information—a series of ones and zeroes. There are three audio file resolutions commonly in use: 8, 16, and 24 bits. 24 bit systems are commonly used these days.

To give you an idea of the relevance of the sampling resolution, imagine two people are building a house. One is using a tape measure marked to the nearest foot. The other has a tape measure marked to the nearest inch. Although the house built with the tape measure accurate to the nearest foot may not fall down, the person using the finer scale will build a more accurate house.

Appendix A Audio and MIDI Basics

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Apple 8 manual Digital Conversions, About Bits and Sampling Rates

8 specifications

The Apple iPhone 8, introduced in September 2017, marked a significant evolution in the company's smartphone lineup, bridging the design elements of the past with cutting-edge technology. The iPhone 8 brought several notable features and advancements that enhanced user experience and performance.

One of the most striking design elements of the iPhone 8 is its glass back, a departure from the aluminum unibody design of its predecessors. This transition not only provided a fresh aesthetic appeal but also enabled wireless charging, allowing users to power their devices conveniently without the need for cables. The iPhone 8 supports Qi wireless charging standards, making it compatible with a wide array of wireless charging pads.

Under the hood, the iPhone 8 is powered by Apple’s A11 Bionic chip, which features a six-core CPU. This powerful processor significantly improved the iPhone's speed and efficiency when compared to previous models. The A11 Bionic was designed for machine learning applications and includes a dedicated neural engine, allowing for better performance in tasks such as image recognition and augmented reality experiences.

The display of the iPhone 8 is a 4.7-inch Retina HD display, boasting True Tone technology, which adjusts the screen's white balance based on the ambient light. This feature not only enhances color accuracy but also improves comfort for users by reducing eye strain in various lighting conditions. With a resolution of 1334 x 750 pixels, the display delivers sharp and vibrant visuals.

Camera capabilities on the iPhone 8 also received significant upgrades. The rear 12-megapixel camera features optical image stabilization, providing clearer photos and smoother video recording, even in low light conditions. The introduction of new color filters and a larger sensor allowed for improved photo quality. The front-facing 7-megapixel camera supports 1080p HD video recording and features advanced portrait mode, offering users new ways to create professional-quality selfies.

Another important aspect of the iPhone 8 is its robust security features. The device continued to use Touch ID for biometric authentication, ensuring that users' data remained secure. Additionally, the iPhone 8 was water and dust resistant, rated IP67, which added an extra layer of durability.

In summary, the Apple iPhone 8 successfully combined innovative technology with timeless design. Its wireless charging, powerful A11 Bionic chip, enhanced camera features, and sturdy build quality made it a compelling choice for consumers looking to experience the best of Apple’s engineering prowess.